Enhanced graft healing of high-porosity expanded polytetrafluoroethylene grafts by covalent bonding of fibronectin

Abstract

The effect of covalent bonding of fibronectin on the patency and graft healing of high-porosity expanded polytetrafluoroethylene (ePTFE) grafts was evaluated. Bilateral carotid grafting was performed in ten mongrel dogs using high-porosity (60 microm) ePTFE grafts, 4 cm in length and 4 mm in internal diameter, that either had been pretreated by the covalent bonding of fibronectin (fibronectin grafts) or were untreated (control grafts). The grafts were harvested 4 to 6 weeks after surgery and subjected to macroscopic and light-microscopic observations. There was no significant difference in patency between the fibronectin grafts and the control grafts with rates of 80% and 70%, respectively. The thrombus-free area score was significantly greater in the fibronectin grafts than in the control grafts, at 86.9% vs 34.0%. Furthermore, the pseudointima was better replaced by fibrous tissue in the fibronectin grafts than in the control grafts, being lined with a layer of endothelial-like cells. More transmural tissue ingrowth was evident in the fibronectin grafts than in the control grafts. The covalent bonding of fibronectin improves graft healing by stimulating transmural tissue ingrowth in high-porosity ePTFE grafts.

Improved Healing of Small-Caliber, Long-Fibril Expanded Polytetrafluoroethylene Vascular Grafts by Covalent Bonding of Fibronectin

“…Our preliminary studies on long-fibril ePTFE grafts in canine and porcine models demonstrated that the fibronectin-bonded graft exhibited better graft healing than the nonbonded control graft in the short term of 3-6 weeks. 10,11 We designed this study based on the evaluation and performance standards for arterial prostheses described by Abbott et al 15 We used the canine iliofemoral-tofemoral artery model with a prosthesis 10 cm long and 4 mm in diameter because the paired-site test is feasible and the flow is similar to the femoral artery flow in humans. The improved neointima formation seen in the fibronectin-bonded grafts was not seen in the nonbonded control grafts.…”

“…9 Covalent bonding of fibronectin was prepared as described previously. 10 The grafts were treated with a mixed solution of methyl lithium and hexamethyl phosphoric amide (Aldrich Chemicals, Milwaukee, WI, USA) in argon gas at 0°C for 30 min, leaving the surface defluorinized. This was followed by treatment with methacrylic acid (Wako Pure Chemicals, Osaka, Japan) at 80°C for 4 h. The methacrylic acid was polymerized to the defluorinized surface.…”

“…[3][4][5][6][7][8][9] Recent reports have described several techniques using biological materials to stimulate transmural tissue ingrowth. [10][11][12][13] Our preliminary results on short-term canine and porcine models demonstrated that covalent bonding of fibronectin enhanced the healing of smallcaliber (4 mm), long-fibril (60 µm) ePTFE vascular grafts. 10,11 We conducted this study to investigate the intermediate performance of small-caliber, long-fibril ePTFE vascular grafts pretreated with covalent bonding of fibronectin, focusing on the histomorphometric changes in the cellular and acellular elements of the graft structure.…”

Prosthetic vascular grafts: Wrong models, wrong questions and no healing

“…Until 10 years ago, approximately 90% of prostheses in large animal models were as short as 5.571.2 cm (Dacron and expended polytetrafluoroethylene (ePTFE)) and 4.571.7 cm polyurethanes (PU), with a median implantation periods of 91.8717.3 days for Dacron grafts, 60.079.36 days for polytetrafluoroethylene (PTFE) grafts [11] and 907127.1 days for PU grafts. In more recent years, slightly longer grafts were implanted (64% were still shorter than 7 cm) and observation periods became shorter (medians: 28.078.9 and 14.0718.7 for ePTFE and Dacron, respectively) [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. In the small proportion of studies where truly long prostheses were implanted, they were either aorto-aortic [30][31][32][33][34][35], aorto-iliac [36][37][38][39] or aorto-femoral [40].…”

Osteoblast behavior on polytetrafluoroethylene modified by long pulse, high frequency oxygen plasma immersion ion implantation

“…Coating the inner surface with a thin layer of proteins (e.g. fibronectin) [9,10] is an effective method to enhance the autologous endothelialization of PTFE-based vascular grafts. As a result, the risk of thrombosis of small-caliber prosthesis is limited.…”